1. Field of the Invention
Embodiments of the present invention relate generally to rolling mills producing hot rolled bar and rod products, and more particularly to the operation of a so-called MORSHOR® system for decelerating and temporarily accumulating such products between successive rolling stages.
2. Description of Related Art
A MORSHOR® system for the deceleration and temporary accumulation of hot rolled bar and rod products is disclosed in U.S. Pat. No. 7,021,103, the description of which is herein fully incorporated by reference. In this system, a length of the hot rolled product is decelerated in the course of being passed through the rotating curved guide of a coiler. The product exits the coiler at a reduced velocity and is delivered to and progressively accumulated on a cylindrical drum as a helical formation of rings. The drum is rotated to continuously unwind the accumulating product at the reduced velocity. The orderly unwinding of the product from the rotating drum is dependent to a large extent on maintaining a stable ring formation.
But, experience has shown that after the tail end of the product exits the coiler, the last rings deposited on the drum become unstable, with erratically increased diameters caused by a combination of factors, including lost tension, centrifugal forces, and elastic deflection. The larger rings tend to overlap and cross over each other. This in turn can upset the unwinding process, resulting in a malfunction commonly referred to as a “cobble.”